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All IPCC definitions taken from Climate Change 2007: The Physical Science Basis. Working Group I Contribution to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Annex I, Glossary, pp. 941-954. Cambridge University Press.

Posted on 21 February 2011 by dana1981

On 28 January 2011, 18 climate scientists sent a letter to US Congress urging them to "take a fresh look at climate change" and the threats that it poses to the USA and the world. In response, a group of "skeptic" scientists issued a "rebuttal" on 08 February 2011. The rebuttal letter referenced two documents - a report issued by co2science.org entitled 'Carbon Dioxide and Earth's Future: Pursuing the Prudent Path', and the NIPCC report. According to the letter, these two reports show a "profusion of actual observations of the workings of the real world showing little or no negative effects of the modest warming of the second half of the twentieth century", thus suggesting that the "prudent path" forward is to continue with business as usual.

Missing the Point

The key to this "rebuttal" - and where it misses the point entirely - is in its argument that the "modest warming" thus far has not resulted in terribly negative consequences. From this the "skeptics" infer that continued warming will also not result in terribly negative consequences, and this is where they go wrong.

It's true that the consequences of anthropogenic climate change so far have been manageable. It's also true that global surface air temperatures have only increased about 0.8°C over the past century. On a century timescale, this is actually quite a large and rapid warming, and let's not forget that based on the greenhouse gases we've emitted to this point, we've already committed the planet to an additional 0.6°C warming, nearly twice as much as the "modest warming" thus far.

But we're not particularly concerned about current temperatures or the current climate. In fact, if we could maintain the climate and average global temperature at today's levels, everybody would be thrilled. The consequences of climate change so far have probably been more bad than good, but compared to the warming and climate change to come, our current temperatures and climate are quite manageable.

However, a business-as-usual scenario will not maintain the current temperature or climate. Quite the opposite, in fact. While the planet has only warmed about 0.8°C over the past century, the IPCC projects that in a business-as-usual scenario, the planet will warm 2.5–4°C over the next century. That's a net warming in the ballpark of 3 to 5 times as much as over the 20th century. A major factor that the "skeptics" are missing is the massive amount of heat which is going into the oceans, which is slowing the warming of the surface air, for the time being. But eventually, after atmospheric greenhouse gas levels stabilize, the planet will reach equilibrium and that unrealized surface air warming "in the pipeline" will happen. And to eventually stop global warming, we have to stabilize atmospheric greenhouse gas levels first!

Stop Poking the Bear

Suggesting that we should continue in a business-as-usual scenario because climate change so far hasn't been bad is like saying that because lightly poking a sleeping bear with a stick didn't awaken it, we should try throwing rocks at it.

A Little Graphical Perspective

Let's try to put what these "skeptics" are suggesting into perspective. In the figure below, the black line with blue error bars represents the instrumental temperature record, and surface air temperature change from 1900 to 2010. This is the warming thus far which hasn't had terribly bad consequences. The red line with yellow range represents the warming to come over the next 90 years in one of the more moderate IPCC business-as-usual emissions scenarios (A1B - rapid global economic growth with a balanced emphasis on all energy sources).

Note that even in Scenario B1, which involves "a high level of environmental and social consciousness combined with a globally coherent approach to a more sustainable development", warming in the 21st Century exceeds that of the 20th Century. In the business-as-usual Scenarios A1F1 and A2, global warming and climate change absolutely dwarf the changes over the past 1,500 years.

Prudent Path Week

In light of the information discussed above, we believe the true "prudent path" is to attempt to significantly reduce global greenhouse gas emissions. In the USA, this will probably involve implementing some sort of carbon pricing mechanism. But the bottom line is that continuing on a business-as-usual path is not prudent, it is exceptionally risky. Arguing that future warming will not be dangerous because the warming thus far has not been significantly damaging, as the "skeptics" did in their letter to US Congress, is illogical and incorrect.

Over the next week we will examine some of the arguments made in the Prudent Path and NIPCC documents, some of the contradictions therein, and further illustrate why business-as-usual is actually a very imprudent path.

Comments

I must disagree with two points: first on sea level rise. There exists no reliable way to detect it and the best available methods show little to no rise
Second, GCM hindcasts and projections, have in peer review to be shown to be unreliable.

I believe that your exclusive focus on the single measure of Annual Global Mean Temperature of the lower atmosphere understates the impacts that the increased greenhouse effect driven by mankind's activities has had since the onset of the Industrial Revolution. As we all know, the world's oceans have absorbed most of the additional energy generated. The Earth's climate systems have been "charged" in ways that we are just beginning to observe, measure, and comprehend.

Arrogance and nihilism seem to be common attributes of many "sceptics"- the ones for whom scepticism means a choice not believe the evidence- "If AGW is real, then I should able to see it, and its consequences should affect me!"

Its not arrogant and nihilistic to look at all the evidence, including evidence which may not support man made climate change, and including for example the strong scientific evidence that multi decadal ocean current oscillations have a large influence on the climate. Also the fact that greenhouse radiation can only warm a few millimetres of the ocean surface. It seems ridiculous to react to slight changes in atmospheric temperature when the oceans have a hundred times the heat capacity.

Perhaps its easier for some to draw cartoons of drowning pet dogs than to study the science without political bias.

And has anyone answered my question on population growth ? If population doubles in the next 50 years then my efforts to walk to work to save the polar bears will have been in vain !

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Response:"...including for example the strong scientific evidence that multi decadal ocean current oscillations have a large influence on the climate"

Climate scientists are well aware that ocean cycles affect climate. You make a good point - it's a very good idea to examine what's happening to the oceans as they have a much greater heat capacity than the atmosphere (in fact, over 90% of global warming is going into the oceans). So when we take a close look at the ocean, what do we see?

Firstly, we find globally, the oceans are building up heat. This cannot be explained by ocean cycles - it can only be explained by the planet being in energy imbalance. Our climate is accumulating heat:

The pattern of ocean warming provides much information also - we see heat penetrating from the surface into the deep waters in all the oceans of the world. Peer-reviewed research into this warming pattern found "the observed ocean heat-content changes are consistent with those expected from anthropogenic forcing, which broadens the basis for claims that an anthropogenic signal has been detected in the global climate system." (Barnett 2007).

Dana, my disagreements are well supported in peer review literature and textbooks. Are you familiar with GIA?

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Moderator Response: [muoncounter] For those who might not be familiar, Chemist1 is most likely referring to glacial isostatic adjustment, the process of restoring gravitational equilibrium to land surfaces formerly buried by kilometers-thick ice sheets. The history of this idea goes back to Celsius in 18th century Sweden; it is extremely well-documented.

Hmmm but if you are right about the oceans, then we're still doomed because of the population growth. And no politician will attempt to tackle that one. I'm still a bit sceptical though - why do politicians and media show us pictures of glaciers collapsing into the sea when that's what glaciers do ! Or polar bears standing on icebergs in the summer ! Funny how my taxes have gone up on the back of global warming.

I reckon we'll stop using fossil fuels when there's none left.

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Moderator Response: [muoncounter] If you are interested in ice, see the thread Basic overview of melting ice and comment there. You will find that what glaciers are supposed to do is both 'grow' and collapse into the sea; what we have now is lacking the growing part. But blaming global warming for your tax increase? That's a new one -- and certainly not the topic here. Have a look at Carbon pricing cost vs. benefits.

Unless you're living in a mainland European country, I doubt very much that your claim is true-as Governments in every other industrialized Country are very much joined at the hip to the Coal/Oil Industry. Here in Australia, $10 billion per annum of tax-payers money is effectively shoveled into the pockets of the fossil fuel industry-in direct & indirect subsidies-but listen to the politicians *scream* if you suggest giving even 1% of that kind of money to the renewable energy industry.

Bibliovermis, you're absolutely right - I had second thoughts about that post almost immediately after I hit the "submit" button - luckily, the mods here are on the ball and deleted it. :-)

Back on topic - the rate of change projected by all the climate models is very high. A common skeptic argument is that there have been large changes in climate previously. Does anyone know of a chart which plots, say, the temp rise at the end of the last ice age (even just the steepest 1,000 years) against the temp profile as presented in Figure 2 above?
I should probably dig up the source data and chart it myself - I'd like to do the comparison for a presentation I'm putting together for work. CO2 & temp would be a useful pair of charts to illustrate how what's happening now differs from past episodes of climate change.

There's also an interesting post over at ClimateSight about the potential for mass extinction as a result of warming events.

Chemist1 @ 16: I haven't read through that paper yet (and I suspect the statistical discussions are beyond my skills in that area), but the site selection immediately leaps out at me as being very, well, odd for Australia. For comparison of precipitation, for example, 3 out of 4 sites in Australia are in the "red centre" - very sparsely populated areas which get very irregular rainfall. It seems very odd, considering the high density of good weather records in the rest of the country...

@mod response at 15: thanks, but I was mostly commenting on the fact that there doesn't appear to be a handy link to those graphics anywhere on the standard page layout - I've previously found it by searching for the blog posts that mention it.

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Moderator Response: [DB] Fair point. While the link I provided originally appeared in this blog post, they seem to be unreferenced anywhere easily findable. A fix is in the pipeline; stay tuned for future developments.

How hot is Earth? The Worldwide Surface Temperature speaks for itself, even when it is derived from multiple sources. But then I expect that the skeptic solution would be to shoot the bear (after provoking it with stones).

So, here global climate is being discussed, and then a paper trying to model local weather with (limited selection of) global climate models is being offered as a proof that models don't work. If one would like to show that models don't work globally, simplest method would be to do a global analysis with them.

We of course all know here that when a proper global analysis is being done, the models give quite accurate result. This is actually quite a remarkable achievement considering how crude the models are compared to the real Earth system. Models also do regionally rather well as can be seen in the link I gave. However, it is not expected that models should recreate the weather of every point of the Earth accurately. That would be expecting miracles.

Chemist1 - No, I was referring to the paper you linked at #16. I had a quick look at it, and while I don't know how or why the authors chose the sites they did, I know enough about Australia to think that their choice of stations was rather odd. I can't comment much on the choice of sites in th US, but I'd second the comments above that comparing results of global climate models to records for individual stations is missing the point, and shows a fundamental misunderstanding of what those models tells us.
If you were comparing a local climate model, or even a regional one, you might have a bit of a case, but the broad-scale averaging required for the global models means you should only compare them with measurements averaged over wide areas.
Or so I understand it, not being a climate scientist myself.

Maybe skeptics could be more easily swayed if instead of presenting temperature "anomaly", NASA (or whoever) maintained and published an annual temperature-second check sum based on some stable temperature measurements sampled around the globe, integrating temperature over time as sampled in weather stations in a continous manner. With the internet, and so many computers out there, this should be possible. In doing so, there would be no need to factor out the effects of urban heat islands, etc. as they all form a part of global warming, (unless of course this data ran counter to an agenda of some kind.) If set up properly, all that would matter then was the data looking forward and that which was maintained from when the system was set up, so that historical proxy data going back 500 or 1000 years would become irrelevant.

By defining a grand check sum, the term "global warming" might actually mean something, regardless of whether climate was cooling or warming somewhere.

RSVP@26 wrote: "Maybe skeptics could be more easily swayed if instead of presenting temperature "anomaly", NASA (or whoever) maintained and published an annual temperature-second check sum based on some stable temperature measurements sampled around the globe"

GISSTEMP is exactly NASAs best attempt at a "stable temperature measurement sampled around the globe". All an "anomaly" means is that the average value over some well defined baseline period has been subtracted. I has no effect whatsoever on trends etc, and I have no idea why skeptics have a problem with the data being presented as an anomaly (for instance the need to put it in quotes).

Do Spencer and Christy also need a second check sum, given that they also provide the UAH data as an anomaly?

DM #27
Is there a particular reason why the data has to be tinkered with? Why not just publish a number? Whatever the number, it should be increasing slowly. Assuming the number is valid, it should just be a matter of dividing it by the number of samples, and the difference of this result every year should be some small number that jives with the anomaly curve in Figure 1.

RSVP: "skeptics could be more easily swayed if instead of presenting temperature "anomaly""

This objection to a temperature anomaly seems to pop up every once in a while. I don't understand why it's an issue. The anomaly concept is simple enough: It's 'usually' some average M, now its +1 more than M; the anomaly is that difference.

But you touch on a more basic issue: Can skeptics be swayed? I suppose the answer depends on what the skeptic means when he or she self-identifies as a 'skeptic'. Those who are ideologically driven, have closed their minds to new ideas and/or are living in fear that 'they are all out to get us' do not sway. This seems to describe the majority of those who show up here calling themselves 'skeptics;' a few comments in and they show their true colors. Every once in a while, you run into a 'true skeptic' - one who has an open mind; it's a very refreshing change.

Contemporary skepticism (or scepticism) is loosely used to denote any questioning attitude, or some degree of doubt regarding claims that are elsewhere taken for granted. Usually meaning those who follow the evidence, versus those who are skeptical of the evidence (see: Denier)

sgmuller @28: I suspect Marcus is referring to this UTS study [pdf], which estimates total fossil fuel subsidies in Australia to be around $8.9 billion per year, most of which goes to oil (see table on p.33).
The subsidies on electricity to aluminium smelters are estimated to be worth $195-232 million per year (table p.17, discussion p.18), but the current figure may be $100m higher due to subsidies to the new(ish) Aldoga smelter near Gladstone.

RSVP@29 There are several good reasons for doing so. Firstly if you want to compare surface temperatures (e.g. GISTEMP/HadCRUt) against satelite data (e.g. UAH/RSS), then the anomalies won't have a relative offset of (IIRC) about ten degrees (becuase the satelite measurements are the temperature of a fairly thick slice of the trophosphere and temperatures decrease with altitude, so the lowere trophosphere temperatures are much colder than the surface). To a lesser extent, you will also get offsets between different surface records, becuase of e.g. handling of the poles, which would also be misleading. Secondly, climatologists are generally interested in trends and changes, in which case the baseline offset is irrelevant, looking at an anomaly just helps focus on what is important without being distracted by irrelevant detail.

If you want to have "the number", just add on the baseline offset for the particular record you are interested in, and you will have it. However, if you think measuring the Earths temperature is a straightforward matter, you are greatly mistaken, see e.g. Trewin (2010) for a very readable review of the need for homogenization etc.

Actually, those trends are 'the numbers' that should be the focus. Figure 1 in Monckton Myths#12 presents an excellent example: the number +6.3 degrees per century should be enough to sway even the most cold-hearted skeptic.

Or Table 1 in the same post, where 8 of the 10 warmest years in the Arctic temperature record occurred this decade. How do the so-called skeptics usually respond to that? With stories of uncomfortable seals from 1922 or a ship frozen in the ice from 1850.

I suppose its easier to laugh about how much those anecdotes 'prove' than actually think about the consequences of our actions.

I have seen the "anomaly" issue raised many times by skeptics. I think it is partially that it suggests to the layperson that the use of the word "anomaly" implies that the records in someway demonstrate that recent temperatures are anomalous in some way, which of course it doesn't, it is just that the word "anomaly" has a specific technical meaning in climatology. The genuinely skeptical, once it has been explained that "anomaly" is not intended to (and does not) imply "anomalous", generally stop worrying about it. It only needs basic numeracy skills to see that subtracting an offset has no impact on the argument either way - just as the warming would be the same whether we gave the temperature in degrees centigrade or degrees Kelvin.

In terms of how much warmign is still to come, there's the "unrealized" warming that still has to make its way out of the ocean as the planet equilibrates, but there's also the cooling effect of aerosols: They will most likely be cleaned up before we get rid of CO2 emissions. As aerosol pollution will be cleaned up, more and more of the "masked" warming will become apparent.

By "the consequences of anthropogenic climate change so far have been manageable" I presume you mean relatively in comparison to what will happen. Alpine glaciers have melted dramatically for over a century now. Sea water's acidity increased and several species alredy experience difficulties forming their shells and skeletons, and these species happen to be right at the beginning of the marine food chain.

Chemist1,
I read your reference. The authors do not like global climate models. It is published in a relatively small journal and has not received much support from other scientists. Gavin Schmidt(who is published in high visibility journals) here comments on their methodology from their previous paper. The results you cited are certainly not the consensus of the field.

I find it difficult to determine what your objections are. If you specify what your objections are perhaps we can address those issues. Do you claim that all models are unreliable? Comparing for example Dr Hansens 1989 projections to what has been observed the projections are close to reality see models are unreliable.

Moderator Response: [muoncounter] See It's aerosols
It's helpful if you avoid declaratory statements like this one; please provide some substantiation or citation when commenting on the correct thread.

I will continue my discussion on models in the appropriate thread. I will say this though: the journal in question is not so small and there is support of the work in science and climate science. More on that in the models are unreliable thread.

I wonder how far AGW proponents should get involved in the whole “unprecedented” discussion. It is a side issue, and while deniers are losing every argument, they are winning the battle, if only by wasting precious time. Even if it can unquestionably proven that current global temperatures are higher than during the MWP, I’m sure they will come up with some other, earlier period in history when the earth used to be warmer. This is a game that can continue forever.

The earth is 4,5 billion years old and has had – some pretty extreme climates, to say the least. In the past the earth has been a giant snow ball with an average temperature of -50 degrees. It has also been a molten ball of lava, with a 1200 degrees surface temperature. So no matter how hot it is going to get on earth, it is never going to be “unprecedented”.

While your argumentation about the incompatibility of large temperature changes and low climate sensitivity is correct, I don’t think it addresses the underlying assumption of the “unprecedented” argument used by skeptics.

What is this “unprecedented” claim really about and why does it appear so often in skeptical arguments ? As far as I can tell, the implied argumentation behind it is: “If I can prove that in the past the earth was warmer than today due to natural causes, the present warming might be due to natural causes as well, and there is nothing to worry about.”

This is actually a valid reasoning if your understanding of the climate is zero. When lacking any other information, it is a crude way to determine if the current climate still falls within a range that can be considered as “normal”.
So it is a perfectly reasonable thing to do if you don’t have the information, but it is irrational behavior if you do have more detailed information at your disposal, which you choose to ignore.

Climate science takes into account all available information to explain all climate changes, past or present, warming or cooling. If we can explain and predict all climate changes of the past and the present, by means of all the known forcings (human and natural) and feedbacks, this means we understand the climate and also have a pretty good idea of how it is going to evolve.
Scientists have to fit the pieces of the puzzle together and check if there are any missing pieces, any holes in our understanding (e.g. warming or cooling that cannot be explained by the current theories). And as it appears the puzzle cannot be made complete without taking the role of CO2 into account.

No skeptical theory exists that is able to successfully explain and predict past and current climate changes, leaving CO2 out of the equation.

I’m sorry if this all sounds too obvious, but I think many people just don’t know these things.

Every now and then I'm struck by an observation one of our commenters makes. With regard to "skeptics", Ann makes this observation:

"...if your understanding of the climate is zero."

Obviously Ann is not applying this to everyone posting here. Legitimate seekers of knowledge become obvious in short order; the obverse as well. It should be painfully obvious to readership which parties comes here in good faith to learn...and which do not (have any intentions to learn).

Over the past several days I have participated in discussions over several threads as many of us have. I have seen many very well thought out and well presented arguments with the best intentions of helping all to understand the many aspects of climate science.

Conversely, I have observed many posts that seem to ignore the most basic principles of physics as well as the many requests to look at data and citations presented to them.

Many contrarian arguments have been thoroughly debunked by addressing specific questions and providing scientifically supporting evidence only to have the originator of the argument to return and say their question was not addressed.

I know many posters here as well as I have become somewhat frustrated with the experience. For the past 24 hours I have only observed posts from the "Recent Comments" page and begin to look at this from a whole new prospective. No doubt it was difficult for me not to respond to some of the posts, but I begin to realize something very important.

Anyone coming to this site seeking information and understanding with an open mind can easily see what is happening in the climate debate. One side presents only science with supporting evidence and references from the scientific community. The other side continously ignores the information being presented and even refuses to read any of the many articles presented on this site already addressing their questions. Any open minded person visiting this site whether they post or not can easily see this and separate the wheat from the chaff. In my opinion, I think the contrarians are their own worst enemy, if by nothing else, the tone presented in their own posts. As someone said in the "Meet The Denominator" thread, "you are the gift that keeps on giving".

Understand my above comments apply only to those posters who have no intention of engaging in meaningful debate and not the true skeptics who wish to discuss and exchange ideas.

Thank you John, Moderators and everyone connected with SkS for following the "proper path", rather than the "prudent path", with such a high quality site for us all to learn and enjoy.

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Moderator Response: [Daniel Bailey] On behalf of John and the other moderators and the large community of regular posters & commentators (not to mention the lay readership at large) here: Thank you. You are a breath of fresh air & have succinctly summed up the nature and flavor of the debate going on here.

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